The damping of vibration and support of instrumentation during launch and acceleration of aircraft or spacecraft are two major issues in mechanical design of sensitive cryogenic instruments. Because of the high sensitivity of such cryogenic instruments to acceleration and vibration, and the extremely limited amount of coolant supply for such instruments, conventional supporting and damping techniques used during launch are unacceptable.
Conventional damping means produce too much heat within the cold chamber for the cryogenic instrument and a rigid supporting structure may cause damage to the instrument when the supporting platform is subjected to high accelerations or vibrations. There is therefore a need for a supporting system without any physical contact of the instrument from outside the cold chamber and with vibration damping that does not produce heat within the cold chamber.
Superconductive materials have been known since the beginning of the century. The most widely used demonstration of superconductive material involves the levitation of magnets over a superconductor. When it is cooled below the critical temperature T.sub.c of the material, the superconductor becomes perfectly diamagnetic. The interior of the superconductor thus experiences an expulsion of magnetic flux.
This effect discovered by Walther Meissner in 1933 manifests itself by producing a force that tends to repel the magnetic flux source. If the flux source is rigidly supported, that force causes a levitation effect on the superconductor, thus producing a free floating superconductor. This free floating effect was first disclosed in U.S. Pat. No. 3,327,265 in 1967.
Prior to 1986, applications of superconductors were limited due to the extreme low operating temperatures required by the superconductors. With the discovery of high T.sub.c superconductor materials that operate in the 90-100K range, which is higher than liquid nitrogen's boiling temperature, there was a renewed interest in applications for superconductors. The Meissner effect used for levitation is one application.
One such levitation application was disclosed in U.S. Pat. No. 4,797,386. A superconductor and magnet were used to induce a separation useful in creating low friction bearings. Another such levitation application disclosed in U.S. Pat. No. 4,879,537 employed magnetic field concentration and superconductive material for free floating an external load. U.S. Pat. No. 5,023,497 discloses another example of the Meissner effect used to generate unidirectional force in response to a current controllably conducted through a superconductor.
High T.sub.c superconductor materials are ideal for use of the Meissner effect in levitation of cryogenic instruments since the instruments already require cooling to a temperature below the T.sub.c of the superconductive materials. The use of superconductors for levitation support and vibration damping of cryogenic instruments is therefore feasible during launch and high acceleration intervals.
Although the use of interacting magnetic fields to produce levitation for load suspending purposes in general is well known, the combination of the Meissner effect of the superconductor in the cold chamber and vibration damping techniques discussed below have not been known to those skilled in the art of using the Meissner effect for levitation.